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/* Handle faults in the signal thread.
Copyright (C) 1994-2023 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
#include <hurd.h>
#include <hurd/signal.h>
#include "hurdfault.h"
#include <errno.h>
#include <string.h>
#include <setjmp.h>
#include <stdio.h>
#include <thread_state.h>
#include "faultexc_server.h" /* mig-generated header for our exc server. */
#include <assert.h>
jmp_buf _hurdsig_fault_env;
struct hurd_signal_preemptor _hurdsig_fault_preemptor = {0};
/* XXX temporary to deal with spelling fix */
weak_alias (_hurdsig_fault_preemptor, _hurdsig_fault_preempter)
static mach_port_t forward_sigexc;
kern_return_t
_hurdsig_fault_catch_exception_raise (mach_port_t port,
thread_t thread,
task_t task,
#ifdef EXC_MASK_ALL /* New interface flavor. */
exception_type_t exception,
exception_data_t code,
mach_msg_type_number_t codeCnt
#else /* Vanilla Mach 3.0 interface. */
integer_t exception,
integer_t code, integer_t subcode
#endif
)
{
int signo;
struct hurd_signal_detail d;
if (port != forward_sigexc
|| thread != _hurd_msgport_thread || task != __mach_task_self ())
return EPERM; /* Strange bogosity. */
d.exc = exception;
#ifdef EXC_MASK_ALL
assert (codeCnt >= 2);
d.exc_code = code[0];
d.exc_subcode = code[1];
#else
d.exc_code = code;
d.exc_subcode = subcode;
#endif
/* Call the machine-dependent function to translate the Mach exception
codes into a signal number and subcode. */
_hurd_exception2signal (&d, &signo);
return HURD_PREEMPT_SIGNAL_P (&_hurdsig_fault_preemptor, signo, d.exc_subcode)
? 0 : EGREGIOUS;
}
#ifdef EXC_MASK_ALL
/* XXX New interface flavor has additional RPCs that we could be using
instead. These RPCs roll a thread_get_state/thread_set_state into
the message, so the signal thread ought to use these to save some calls.
*/
kern_return_t
_hurdsig_fault_catch_exception_raise_state
(mach_port_t port,
exception_type_t exception,
exception_data_t code,
mach_msg_type_number_t codeCnt,
int *flavor,
thread_state_t old_state,
mach_msg_type_number_t old_stateCnt,
thread_state_t new_state,
mach_msg_type_number_t *new_stateCnt)
{
abort ();
return KERN_FAILURE;
}
kern_return_t
_hurdsig_fault_catch_exception_raise_state_identity
(mach_port_t exception_port,
thread_t thread,
task_t task,
exception_type_t exception,
exception_data_t code,
mach_msg_type_number_t codeCnt,
int *flavor,
thread_state_t old_state,
mach_msg_type_number_t old_stateCnt,
thread_state_t new_state,
mach_msg_type_number_t *new_stateCnt)
{
abort ();
return KERN_FAILURE;
}
#endif
#ifdef NDR_CHAR_ASCII /* OSF Mach flavors have different names. */
# define mig_reply_header_t mig_reply_error_t
#endif
static void
faulted (void)
{
struct
{
mach_msg_header_t head;
char buf[64];
} request;
mig_reply_header_t reply;
extern int _hurdsig_fault_exc_server (mach_msg_header_t *,
mach_msg_header_t *);
/* Wait for the exception_raise message forwarded by the proc server. */
if (__mach_msg (&request.head, MACH_RCV_MSG, 0,
sizeof request, forward_sigexc,
MACH_MSG_TIMEOUT_NONE, MACH_PORT_NULL)
!= MACH_MSG_SUCCESS)
__libc_fatal ("msg receive failed on signal thread exc\n");
/* Run the exc demuxer which should call the server function above.
That function returns 0 if the exception was expected. */
_hurdsig_fault_exc_server (&request.head, &reply.Head);
if (reply.Head.msgh_remote_port != MACH_PORT_NULL)
__mach_msg (&reply.Head, MACH_SEND_MSG, reply.Head.msgh_size,
0, MACH_PORT_NULL, MACH_MSG_TIMEOUT_NONE, MACH_PORT_NULL);
if (reply.RetCode == MIG_BAD_ID)
__mach_msg_destroy (&request.head);
if (reply.RetCode)
__libc_fatal ("BUG: unexpected fault in signal thread\n");
_hurdsig_fault_preemptor.signals = 0;
longjmp (_hurdsig_fault_env, 1);
}
static char faultstack[1024];
/* Send exceptions for the signal thread to the proc server.
It will forward the message on to our message port,
and then restore the thread's state to code which
does `longjmp (_hurd_sigthread_fault_env, 1)'. */
void
_hurdsig_fault_init (void)
{
error_t err;
struct machine_thread_state state;
mach_port_t sigexc;
/* Allocate a port to receive signal thread exceptions.
We will move this receive right to the proc server. */
err = __mach_port_allocate (__mach_task_self (),
MACH_PORT_RIGHT_RECEIVE, &sigexc);
assert_perror (err);
err = __mach_port_allocate (__mach_task_self (),
MACH_PORT_RIGHT_RECEIVE, &forward_sigexc);
assert_perror (err);
/* Allocate a port to receive the exception msgs forwarded
from the proc server. */
err = __mach_port_insert_right (__mach_task_self (), sigexc,
sigexc, MACH_MSG_TYPE_MAKE_SEND);
assert_perror (err);
/* Set the queue limit for this port to just one. The proc server will
notice if we ever get a second exception while one remains queued and
unreceived, and decide we are hopelessly buggy. */
#ifdef MACH_PORT_RECEIVE_STATUS_COUNT
{
const mach_port_limits_t lim = { mpl_qlimit: 1 };
assert (MACH_PORT_RECEIVE_STATUS_COUNT == sizeof lim / sizeof (natural_t));
err = __mach_port_set_attributes (__mach_task_self (), forward_sigexc,
MACH_PORT_RECEIVE_STATUS,
(mach_port_info_t) &lim,
MACH_PORT_RECEIVE_STATUS_COUNT);
}
#else
err = __mach_port_set_qlimit (__mach_task_self (), forward_sigexc, 1);
#endif
assert_perror (err);
/* This state will be restored when we fault.
It runs the function above. */
memset (&state, 0, sizeof state);
MACHINE_THREAD_STATE_FIX_NEW (&state);
MACHINE_THREAD_STATE_SET_PC (&state, faulted);
MACHINE_THREAD_STATE_SET_SP (&state, faultstack, sizeof faultstack);
err = __USEPORT
(PROC,
__proc_handle_exceptions (port,
sigexc,
forward_sigexc, MACH_MSG_TYPE_MAKE_SEND,
MACHINE_THREAD_STATE_FLAVOR,
(natural_t *) &state,
MACHINE_THREAD_STATE_COUNT));
assert_perror (err);
/* Direct signal thread exceptions to the proc server. */
#ifdef THREAD_EXCEPTION_PORT
err = __thread_set_special_port (_hurd_msgport_thread,
THREAD_EXCEPTION_PORT, sigexc);
#elif defined (EXC_MASK_ALL)
__thread_set_exception_ports (_hurd_msgport_thread,
EXC_MASK_ALL & ~(EXC_MASK_SYSCALL
| EXC_MASK_MACH_SYSCALL
| EXC_MASK_RPC_ALERT),
sigexc,
EXCEPTION_STATE_IDENTITY,
MACHINE_THREAD_STATE);
#else
# error thread_set_exception_ports?
#endif
__mach_port_deallocate (__mach_task_self (), sigexc);
assert_perror (err);
}
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